Turbine engines, and particularly gas or combustion turbine engines, are rotary engines that extract energy from a flow of combusted gases passing through the engine onto a multitude of rotating turbine blades. Gas turbine engines have been used for land and nautical locomotion and power generation, but are most commonly used for aeronautical applications such as for aircraft, including helicopters. In aircraft, gas turbine engines are used for propulsion of the aircraft. In terrestrial applications, turbine engines are often used for power generation.
Gas turbine engines for aircraft comprise multiple compressor stages designed with a plurality of bands of blades, generally circumferentially arranged on disks forming the rotor, rotated by a rotor and bands of static vanes disposed between the rotating blades. The compressor stages compress the air that is then moved to a combustor and a turbine. Seals are provided between the bands and the rotor, limiting airflow leakage to upstream areas of the compressor, which can reduce efficiency of the system. Additionally, a common practice in turbines, a cooling or purge air flow can be introduced into a rotor to cool the rotor and retard the hot gas path air from entering through openings or gaps in the rotor or between the disks and the static bands.